Suboccipital triangle

RCPMin = Rectus Capitis Posterior Minor (not seen)

RCPMaj = Rectus Capitis Posterior Major

OCS = Obliquus Capitis Superior

OCI = Obliquus Capitis Inferior

NOTE: The suboccipital nerve (C1) and the vertebral artery are found within the suboccipital triangle. Note that the greater occipital nerve (C2) exits inferior to the obliquus capitis inferior and then runs superiorly to pierce the semispinalis capitis and upper trapezius muscles, before entering the scalp, where it provides sensory innervation to the scalp.

ATTACHMENTS:

• The rectus capitis posterior major attaches from the spinous process of C2 to the inferior nuchal line of the occiput.
• The rectus capitis posterior minor attaches from the posterior tubercle of C1 to the inferior nuchal line of the occiput.
• The obliquus capitis inferior attaches from the spinous process of C2 to the transverse process of C1.
• The obliquus capitis superior attaches from the transverse process of C1 to the occiput, between the inferior and superior nuchal lines.

ACTIONS:

• The rectus capitis posterior major extends the head at the atlanto-occipital joint.
• The rectus capitis posterior minor and obliquus capitis superior protract the head at the atlanto-occipital joint.
• The obliquus capitis inferior ipsilaterally rotates the atlas at the atlanto-occipital joint.